1. Field of the Invention
This invention relates to the control of lighting units and in particular to a system for controlling light units within a building.
2. Related Art
Lighting systems within buildings conventionally comprise a plurality of lighting units which are distributed throughout the various rooms of the building. The lighting units are connected by electrical wiring to the electrical mains to provide power for the lighting and also by other wiring to switches which enable the lighting units to be switched on and off as required. The switches are usually mounted on a wall and the wiring connecting the switch to the lighting unit is usually set into the wall. It is not uncommon for the layouts within the rooms of buildings to be changed periodically. This can result in the positions of the switches having to be changed and accordingly, new wiring has to be provided between the lighting units and the switches. As a consequence there is a need to repair the surface of the wall resulting from the damage which is inevitably caused in providing the new wiring and then subsequently redecorating the room. This can be a costly and time consuming exercise.
Furthermore hard wired switches severely limit the way in which a number of switches can be used to control lighting. If more than one switch is to control a light there must be a three way cable connection on all of the switches.
The present invention is concerned with a lighting unit control arrangement which does not require electrical wiring between the switch control and the lighting unit and therefore inter alia obviates the above-mentioned problems.
Techniques for the remote control of lights have been described in, for example, GB-A-2174282, EP-A-0255580, and GB-A-2280291. These arrangements are limited to control within a room and do not provide building wide control.